The variations:

Add the sixth spice i.e. Radhuni/ Ajmod/Wild Celery seeds in half the quantity used for each of the other five ingredients (e.g ½ tsp Radhuni if you have used 1 tsp each of Shorshe, Mouri, Methi, Kalo Jeere and Jeere)...and yes, adding another ingredient makes is Chhoi (six) Phoron. Chhoi Phoron is normally used only for specific dishes like Shukto, Labra etc.